Abstract:

A method of preparing an ophthalmic lens for mounting in a surround of an
eyeglass frame, the surround presenting a generally profiled shape with
an inside face provided with a first engagement ridge or groove and lying
between a rear margin for being turned towards the face of the wearer of
the eyeglass frame and an opposite front margin, the method including:
acquiring the three-dimensional shape of an acquired longitudinal profile
running along the inside face; and shaping the ophthalmic lens so as to
form on its edge face a second engagement ridge or groove extending along
a deduced longitudinal profile of three-dimensional shape calculated as a
function of the shape of the acquired longitudinal profile. The method
further includes acquiring a geometrical characteristic that relates to
the position of the engagement ridge or groove relative to the front
and/or rear margin of the frame, the shape of the deduced longitudinal
profile then also being calculated as a function of the geometrical
characteristic.

Claims:

1-15. (canceled)

16. A method of preparing an ophthalmic lens (120) for mounting in a
surround (110) of an eyeglass frame (100), the surround (110) presenting
a generally profiled shape with an inside face (114) provided with a
first engagement ridge or groove (111) and lying between a rear margin
(116) for being turned towards the face of the wearer of the eyeglass
frame (100) and an opposite front margin (115), the method comprising:a
first acquisition step of acquiring the three-dimensional shape of an
acquired longitudinal profile (P1) running along said inside face (114);
anda step of shaping the ophthalmic lens (120) so as to form on its edge
face a second engagement ridge or groove (123) extending along a deduced
longitudinal profile (P3) of three-dimensional shape that is calculated
as a function of the shape of said acquired longitudinal profile
(P1);wherein the method includes a second acquisition step of acquiring a
geometrical characteristic (H1) relating to the position of the first
engagement ridge or groove (111) relative to said front and/or rear
margin (115 and/or 116) in an axial direction substantially perpendicular
to a general plane of the eyeglass frame (100), and in that the shape of
the deduced longitudinal profile (P3) is also calculated as a function of
said geometrical characteristic (H1).

17. The method of preparation according to claim 16, wherein said
geometrical characteristic (H1) comprises a distance relating to the
position of the first engagement ridge or groove (111) relative to said
front and/or rear margin (115 and/or 116) at least one given
cross-section of the surround (110).

18. The method of preparation according to claim 16, wherein said
geometrical characteristic (H1) comprises distances relating to the
position of the first engagement ridge or groove (111) relative to said
front and/or rear margin (115 and/or 116) at least ten given
cross-sections of the surround (110).

19. The method of preparation according to claim 16, wherein the shape of
the deduced longitudinal profile (P3) is calculated so that at the end of
the shaping step, the ophthalmic lens (120) can be engaged in the
surround (110) in such a manner that the periphery of its front face
(121) is flush with the front margin (115) of the surround (110).

20. The method of preparation according to claim 16, wherein said second
acquisition step is performed by rolling or sliding a feeler (10) along a
generally longitudinal line (P2) of the front or rear margin (115 or 116)
of the surround (110).

21. The method of preparation according to claim 20, wherein said feeler
(10) has three degrees of freedom in movement (R, THETA, Z) for moving in
the three dimensions of space, including freedom to move axially (Z)
along said axial direction during said second acquisition step, and
wherein the positions of the other two freedoms of movement (R, THETA) of
said feeler (10) are controlled as a function of the shape of said
acquired longitudinal profile (P1), and the axial freedom of movement (Z)
of said feeler (10) is controlled independently of the shape of said
acquired longitudinal profile (P1) to act in a return direction so that
the feeler (10) remains in contact with the front or rear margin (115 or
116) of the surround (110).

22. The method of preparation according to claim 21, wherein said other
two freedoms of movement (R, THETA) of the feeler (10) are controlled so
that during said second acquisition step the feeler (10) remains in
register with the first engagement ridge or groove (111), e.g. in
register with the acquired longitudinal profile (P1) in said axial
direction.

23. The method of preparation according to claim 20, wherein the feeler
(10) is fitted with a read head (12) including a V-shaped bearing shoe
(15), and said second acquisition step is performed by engaging said
bearing shoe (15) against the surround (110), and by allowing it to slide
there along in such a manner that two bearing zones (112, 113) of the
bearing shoe (15) slide respectively over the front or rear margin (115
or 116) and against the inside face (114) of the surround (110).

24. The method of preparation according to claim 16, wherein said second
acquisition step is performed by optically feeling the front or rear
margin (115 or 116) of the surround (110).

25. The method of preparation according to claim 16, wherein said second
acquisition step is performed by searching, in a database registry in
which each record is associated with a reference eyeglass frame type and
contains a geometrical characteristic specific to said eyeglass frame
type and relating to the position of the engagement ridge or groove
relative to the front and/or rear margin of the surround, for a record
corresponding to said eyeglass frame (100), and in reading said
associated geometrical characteristic (H1).

26. The method of preparation according to claim 25, wherein, if no record
corresponding to said eyeglass frame (100) is found, said geometrical
characteristic (H1) is acquired by rolling or sliding a feeler (10) along
the front and/or rear margin (115 or 116) of said surround (110) and by
writing said acquired geometrical characteristic (H1) in a new record of
the database registry in association with said eyeglass frame (100).

27. The method of preparation according to claim 16, wherein the first
acquisition step is performed by mechanically feeling along said first
engagement ridge or groove (111) or by optically feeling along said first
engagement ridge or groove (111).

28. The method of preparation according to claim 16, wherein the first
acquisition step is performed by reading a record in a database registry
in which each record is associated with a reference eyeglass frame type
and contains the three-dimensional shape of an acquired longitudinal
profile specific to said reference eyeglass frame type.

29. The method of preparation according to claim 16, implemented by means
of a system comprising firstly a client terminal installed beside a
client and including computer means for computing and transmitting order
data concerning an ophthalmic lens (120), said order data comprising data
relating to said eyeglass frame (100), and secondly a manufacturer
terminal installed beside a manufacturer and including computer means for
receiving and recording the order data transmitted by the client
terminal, and a shaper device for shaping said ophthalmic lens (120) and
designed to implement said shaping step, said second acquisition step
comprising:a step of the client determining said geometrical
characteristic (H1); anda step of the client terminal sending control
data, said data incorporating said geometrical characteristic (H1); anda
step of the manufacturer terminal receiving at least part of said control
data, said part incorporating said geometrical characteristic (H1).

30. The method according to claim 16, implemented by means of a system
comprising firstly a client terminal installed beside a client and
including computer means for computing and transmitting order data
concerning an ophthalmic lens (120), said order data comprising data
relating to said eyeglass frame (100), and secondly a manufacturer
terminal installed beside a manufacturer and including computer means for
receiving and recording the order data transmitted by the client
terminal, and a shaper device for shaping said ophthalmic lens (120) and
designed to implement said shaping step, said second acquisition step
comprising:a step of the client reading a reference for said eyeglass
frame (100);a step of the client terminal sending order data, the order
data incorporating said reference;a step of the manufacturer terminal
receiving said order data; anda step of the manufacturer terminal
searching in a database registry in which each record is associated with
a reference eyeglass frame type and contains a reference of said eyeglass
frame type and a geometrical characteristic relating to the position of
the engagement ridge or groove relative to the front and/or rear margin
of the surround specific to said eyeglass frame type, for a record
associated with the reference read for said eyeglass frame (100).

Description:

TECHNICAL FIELD TO WHICH THE INVENTION RELATES

[0001]The present invention relates in general to the field of eyeglasses
and more particularly to acquiring the shape of a surround of a rimmed or
half-rimmed eyeglass frame for the purpose of machining an ophthalmic
lens for mounting on said eyeglass frame.

[0002]More particularly, the invention relates to a method of preparing an
ophthalmic lens for mounting in a surround of an eyeglass frame, the
surround presenting a generally profiled shape with an inside face
provided with a first engagement ridge or groove and lying between a rear
margin for being turned towards the face of the wearer of the eyeglass
frame and an opposite, front margin, the method comprising: a first
acquisition step of acquiring the three-dimensional shape of an acquired
longitudinal profile running along said inside face; and a step of
shaping the ophthalmic lens so as to form on its edge face a second
engagement ridge or groove extending along a deduced longitudinal profile
of three-dimensional shape that is calculated as a function of the shape
of said acquired longitudinal profile.

TECHNOLOGICAL BACKGROUND

[0003]Part of the skill of an optician consists in mounting a pair of
correcting ophthalmic lenses on an eyeglass frame selected by a wearer.
Such mounting comprises three main operations:

[0004]acquiring the shape of a surround of the eyeglass frame;

[0005]centering the lens, which consists in positioning and in orienting
said lens appropriately in front of the corresponding eye of the wearer;
and then

[0006]machining the lens which consists in cutting away or shaping its
outline to the desired shape, given the shape of the surround and the
defined centering parameters.

[0007]The specific aim of the optician is to shape the ophthalmic lens so
that it can be fitted mechanically to the shape of the surround of the
selected frame, while ensuring that the lens performs the optical
function for which it is designed as well as possible.

[0008]With rimmed eyeglass frames, the surround completely surrounds the
outline of the lens and is referred to as a rim. Shaping includes a
beveling operation that consists in forming all along the edge face of
the lens an engagement ridge that is to engage in a groove, commonly
referred to as a bezel, running around the inside face of the rim of the
eyeglass frame.

[0009]With half-rimmed eyeglass frames, the surround goes around only a
fraction of the outline of the lens and is referred to as a half-rim.
Shaping then comprises a grooving operation consisting in forming along
the edge face of the lens an engagement groove, with a fraction thereof
being designed to be engaged on a ridge running around the inside face of
the half-rim of the eyeglass frame. The lens is held against the half-rim
by a string that is connected to the end of the half-rim and that is
received in the remaining fraction of the engagement groove.

[0010]Generally, in order to ensure that the engagement ridge (or the
engagement groove) does not overlie to the front or rear of the edge face
of the lens, the optician machines the lens so that the engagement ridge
(or the engagement groove) lies substantially halfway across the width of
its edge face.

[0011]Nevertheless, it is found that once the pair of eyeglasses has been
assembled, it does not always present a pleasing appearance, because the
positioning of the lenses in the rims of the frame as determined by the
above-mentioned technical constraints lead to possible differences in the
thicknesses or even in the general curvatures of the two lenses, and to
differences in thickness between the edge of the lens and the
corresponding rim of the frame. This is particularly widespread since
frames come in a very wide variety of shapes.

OBJECT OF THE INVENTION

[0012]In order to remedy the above-mentioned drawback of the prior art,
the present invention proposes a novel method of preparing lenses that
enables an ophthalmic lens to be machined so that the periphery of its
front face lies at a pleasing distance from the front or rear margin of
the surround of the eyeglass frame.

[0013]More particularly, the invention proposes a method of preparation as
defined in the introduction, wherein provision is made for a second
acquisition step of acquiring a geometrical characteristic relating to
the position of the first engagement ridge or groove relative to said
front and/or rear margin in an axial direction substantially
perpendicular to a general plane of the eyeglass frame, and wherein the
shape of the deduced longitudinal profile is also calculated as a
function of said geometrical characteristic.

[0014]To provide a pleasing appearance, it is desirable to position the
ophthalmic lens in the surround of the eyeglass frame in such a manner
that its front face extends at a known distance, preferably a distance
that is constant and zero, from the front margin of the surround.

[0015]To do this, in practice, the second step of acquiring the
geometrical characteristic which corresponds to the distance between the
first engagement groove (or the first engagement ridge) and the front
margin of the surround is performed, and then the lens is machined during
the shaping step in such a manner that the second engagement ridge (or
engagement groove) extends at a distance from the front face of the lens
that is substantially equal to said geometrical characteristic.

[0016]According to a first advantageous characteristic of the invention,
said geometrical characteristic comprises a distance relating to the
position of the first engagement ridge or groove relative to said front
and/or rear margin at at least one given cross-section of the surround.

[0017]As a result, during the shaping step, the second engagement ridge
(or engagement groove) is made in such a manner as to extend at a
distance from the front face of the lens that remains substantially equal
to the distance acquired along its outline. Thus, once the ophthalmic
lens has been engaged in its surround, its front face lies substantially
flush with the front margin of the surround over its entire periphery.

[0018]In a variant, said geometrical characteristic comprises distances
relating to the position of the first engagement ridge or groove relative
to said front and/or rear margin at at least ten given cross-sections of
the surround.

[0019]A surround for an eyeglass frame generally presents a section that
is not uniform along its length, and may for example be slightly twisted.
The distance between the first engagement groove (or first engagement
ridge) and the front margin of the surround along the main axis therefore
varies.

[0020]In this variant, said distance is therefore acquired at a plurality
of sections of the surround so as to take account of these variations
during the shaping step.

[0021]By means of the invention, it is possible in particular to acquire
said distance at a multitude of points around the outline of the
surround, and subsequently to shape the lens and/or make the optical
faces of the lens to measure (by machining or by shaping material) in
such a manner that, once engaged in the surround, its front face comes
flush as well as possible with the front margin of the surround all away
around its periphery.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0022]The following description with reference to the drawings, given by
way of non-limiting example, makes it clear what the invention consists
in and how it may be reduced to practice.

[0023]In the accompanying drawings:

[0024]FIG. 1 is a perspective view of an outline reader appliance of the
invention receiving a rimmed eyeglass frame having two rims;

[0026]FIG. 3 is a section view of the feeler of the outline reader
appliance of FIG. 1 shown feeling the rear margin of the rims; and

[0027]FIG. 4 is a section view of the feeler of the outline reader
appliance of FIG. 1 fitted with a bearing shoe engaged against one of
said rims.

[0028]The object of the present invention is to improve the appearance of
the engagement between an ophthalmic lens and a surround (rim or
half-rim) of a rimmed or half-rimmed eyeglass frame.

[0029]This description relates more particularly to rimmed eyeglass frames
100 (FIG. 1) having two rims 110 that are connected together by a bridge
102, and each of which is fitted with a temple 103.

[0030]The rims 110, also referred to as "surrounds", may present a variety
of shapes (square, oval, elongate, . . . ). It should be understood that
using the term "rim" is not in any way limiting as to the shape of the
element in question. The term "rimmed frame" is thus used in contrast to
"drilled frame" which is used to designate frames having a bridge and two
temples, but not having rims.

[0031]A general plane (not shown) can be defined relative to such a rimmed
eyeglass frame 100, which general plane is orthogonal to the two temples
103 of the eyeglass frame 100 when they are in the deployed position, and
is tangential to the bridge 102 of the frame.

[0032]Each rim 110 is generally profiled in shape, having an inside face
114 bordered by two margins 115 and 116, comprising a rear margin 116 on
the same side of the rim as the branches 103, and a front margin 115
opposite thereto. The rear margin 116 is thus intended to face towards
the face of the wearer of the eyeglass frame 100.

[0033]Conventionally, as shown in FIGS. 3 and 4, the inside face 114 of
each rim 110 has an engagement groove running therealong, here of
V-shaped section, and commonly referred to as a bezel 111.

[0034]The bezel 111 extends along a curvilinear acquired longitudinal
profile P1. This acquired longitudinal profile P1 corresponds to one of
the curves traced along the bezel on one and/or the other of its flanks
and that is substantially parallel to or coincides with the bottom of the
bezel. Here it corresponds to the curve that runs along the bottom of the
bezel 111.

[0035]As shown in FIG. 2, the ophthalmic lens 120 for engaging in the
corresponding rim 110 of the eyeglass frame presents a front optical face
121 that is convex and a rear optical face 122 that is concave. As shown
in this figure, the ophthalmic lens 120 has already been machined and on
its edge face it includes an engagement ridge 123 for engaging in the
bezel 111 of the rim 110. This engagement ridge 123 extends along a
deduced longitudinal profile P3 that is curvilinear and it presents a
uniform section that is V-shaped. The deduced longitudinal profile P3
corresponds to a line that runs along the engagement ridge, i.e. a curve
that extends along one and/or the other of the flanks of the engagement
rim 123 and that is substantially parallel to or coincides with the peak
of the engagement ridge. In this example, it coincides with the peak of
the engagement ridge 123.

[0036]As explained in greater detail below, the three-dimensional shape of
this deduced longitudinal profile P3 (as a function of which the
ophthalmic lens is machined) is deduced from the three-dimensional shape
of the acquired longitudinal profile P1 of the bezel 111 of the rim 100
and as a function of a geometrical characteristic H1 (FIG. 3) that
relates to the position of the bezel 111 relative to the front margin 115
of the rim 110.

[0037]Device

[0038]In order to acquire the three-dimensional shape of the acquired
longitudinal profile P1 and said geometrical characteristic H1, it is
possible to use an outline reader appliance 1, for example the appliance
shown in FIG. 1.

[0039]This appliance comprises a structure 5 covered by a top cover 2 and
serving to receive the eyeglass frame 100.

[0040]The structure 5 includes means for holding the eyeglass frame 100,
which means are formed by two movable jaws 3 associated with pairs of
studs 4 suitable for clamping the rims 110 of the eyeglass frame 100.

[0041]The outline reader appliance 1 also has a feeler 10 provided with a
support rod 11 of longitudinal axis A3 and a reader head 12 adapted to
follow the acquired longitudinal profile P1 of the rim 110 of the
eyeglass frame 100 by keeping in contact therewith while turning about an
axis of rotation A1.

[0042]For this purpose, the feeler 10 can move with three degrees of
freedom relative to the structure 5.

[0043]Two particular arrangements of the reader appliance are described
below that enable the feeler to have these various degrees of freedom,
however these arrangements are merely two embodiments amongst others of
the reader appliance.

[0044]In the arrangement shown in FIG. 1, the outline reader appliance 1
has a plate (not shown) capable of moving in translation on the structure
5 along a transfer axis A2. A turntable 6 is mounted on the plate. The
turntable 6 is suitable for taking up two positions along the transfer
axis A2, each in register with one of the two rims 110 of the eyeglass
frame 100.

[0045]The turntable 6 possesses an axis of rotation A1 defined as the axis
normal to the front face of the turntable 6 and passing through its
center. It is suitable for pivoting about this axis relative to the
plate. The turntable 6 also includes a circularly arcuate oblong slot 7
through which the feeler 10 projects.

[0046]The outline reader appliance 1 also includes actuator means for
moving the plate along the transfer axis A2, for causing the turntable 6
to turn about its axis of rotation 1, for causing the support rod 11 of
the feeler 10 to slide along the slot 7, and for modifying the height of
the feeler head 12 relative to the plane of the turntable 6.

[0047]Finally, the outline reader appliance 1 includes an electronic
and/or computer device 8 serving firstly to control the actuator means of
the outline reader appliance 1, and secondly to acquire and store the
successive positions of the reader head 12 of the feeler 10.

[0048]To summarize, the three degrees of freedom in movement of the feeler
10 in this arrangement comprise freedom to move radially R so that the
feeler 10 can move towards or on the contrary away from the axis of
rotation A1, freedom of the feeler 10 to move circumferentially THETA
[theta] in pivoting about the axis of rotation A1, and freedom to move
axially Z so that the feeler 10 can move up or down relative to the plane
of the front face of the turntable 6.

[0049]As shown in FIGS. 3 and 4, the feeler 10 is fitted with a read head
12 including a feeler finger 14. More precisely, in this example, the
read head 12 has a collar 16 mounted at the end of the support rod 11 and
surmounted by a peg 17.

[0050]The feeler finger 14 extends from the outside face of the collar 16.
It is in the form of a point 14 that extends perpendicularly to the
longitudinal axis A3 of the support rod 11 and that presents a spherical
endpiece 13. The endpiece 13 is for inserting in the bottom of the bezel
111 of the rim 110 and for sliding along the bezel 111 so as to read the
shape of the acquired longitudinal profile P1 of the bezel 111. In a
variant, the feeler finger could be of some other shape, such as a
cylindrical rod or a blade pivoting in a direction orthogonal to the
longitudinal axis A3 of the support rod 11. In a variant, its endpiece
could be rotatably mounted on the point, so that instead of sliding along
the rim, it rolls therealong.

[0051]The collar 16 and the peg 17 are circularly cylindrical about the
longitudinal axis A3 and they present different diameters. The peg 17
thus constitutes a piece of section that is smaller than that of the
collar 16, thus defining a shoulder 15 around the entire periphery of the
collar 16.

[0052]In this embodiment, the shoulder 15 forms a V-shaped bearing shoe 15
adapted to engage said rim 110 so as to slide therealong (FIG. 4).

[0053]To do this, as shown in FIG. 4 and as described in greater detail
below, the read head 12 is controlled in such a manner that the feeler
finger 14 faces inwards, i.e. towards the axis of rotation A1 throughout
the time the rim 110 is being felt by means of the bearing shoe 15.

[0054]By way of example, for this purpose, the read head 12 may present
freedom to move in pivoting so as to be capable of presenting the bearing
shoe 15 facing towards the rim 110 without the feeler finger 14
interfering with the frame 100. In a variant, the outline reader
appliance need not be provided with this freedom to move in pivoting.
Provision could then be made for the read head to be removable and to be
manually mounted on the support rod in two different orientations.
Provision could also be made for two interchangeable read heads, one
carrying the feeler finger and the other carrying the bearing shoe.

[0055]In a variant, in order to simplify the algorithms for controlling
the feeler 10, provision could be made for the read head 12 to be
controlled to have the feeler finger 14 facing outwards, in similar
manner to controlling the feeler finger while it is acquiring the shape
of the bezel 111 by means of the feeler finger 14.

[0056]The above-mentioned bearing shoe is then formed by the side face of
the peg and by the top face of the feeler finger 14.

[0057]In an embodiment that is not shown in the figures, the read head of
the feeler need not have a bearing shoe.

[0058]The second arrangement for the outline reader appliance is not shown
in the figures. By way of example, such an outline reader appliance is
described in document EP 0 291 378 and in document U.S. Pat. No.
4,995,170. In this arrangement, the feeler has three degrees of freedom
to move in translation so as to move in all three dimensions of
three-dimensional space. In particular, it includes means for actuating
the feeler so as to move it along three mutually orthogonal directions.

[0059]In this embodiment, since the feeler does not pivot about an axis of
rotation, it is necessary for it to present circular symmetry to enable
it to feel all of the bottom of the bezel. For this purpose, its read
head may be in the form of a thin disk with its edge face being adapted
for insertion into the bezel.

[0060]In order to prepare the ophthalmic lens 120, it is also known to
make use of a shaper appliance 130 that does not form the specific
subject matter of the present invention. Such a shaper appliance is well
known to the person skilled in the art, and is described for example in
document U.S. Pat. No. 6,327,790 or as sold by the Applicant under the
trademark Kappa CTD.

[0061]As shown in FIG. 2, such a shaper appliance 130 generally comprises
support means, constituted in this example by shafts 131 for holding and
driving the ophthalmic lens 120 in rotation about a blocking axis A4.
Such a shaper appliance also has shaper means, constituted in this
example by a machining tool 132 that is mounted to rotate about a
machining axis A5. In this example, the axis AS is substantially parallel
to the blocking axis A4, but it could equally well be inclined relative
thereto.

[0062]The machining tool 132 and/or the shafts 131 are provided with two
degrees of freedom to move relative to each other, one degree of freedom
that is radial enabling the spacing between the machining axis A5 and the
blocking axis A4 to be modified, and another degree of freedom to move in
axial translation along an axis parallel to the blocking axis A4.

[0063]The shaper appliance 130 also includes an electronic and/or computer
device (not shown) that is provided firstly with means for communicating
with the electronic and/or computer device 8 of the outline reader
appliance 1, and secondly with means for controlling the degrees of
freedom of the shafts 131 and the machining tool 132 to move relative to
one another. For each angular position of the lens 120 about the blocking
axis A4, the electronic and/or computer device serves in particular to
control the radial spacing between the machining tool 132 and the
blocking axis A4, and also the axial position of the edge face of the
lens relative to the working surface of the machining tool 132.

[0064]Specifically, the machining tool 132 is constituted by a shaped main
grindwheel, i.e. a grindwheel presenting a recess, like a negative,
presenting a machining profile that is complementary to the section of
the engagement ridge 123 that is to be obtained in relief on the edge
face of the lens for machining.

[0065]Method of Preparation

[0066]The method of preparing the ophthalmic lens is described below with
reference to the outline reader appliance 1 shown in FIG. 1.

[0067]The method comprises four main steps. In particular, it comprises a
first step of acquiring the shape of the acquired longitudinal profile P1
of the bezel 111, a second step of acquiring the geometrical
characteristic H1, a step of deducing the shape of the deduced
longitudinal profile P3 of the engagement ridge 123, and a step of
shaping the ophthalmic lens 120 to have said deduced longitudinal profile
P3.

[0068]During the first step, the eyeglass frame 10 selected by the future
wearer is engaged in the reader appliance 1 (FIG. 1). For this purpose,
the frame 100 is inserted between the studs 4 of the jaws 3.

[0069]The feeler, which is initially positioned in the center of the
turntable 6, beneath the eyeglass frame 100, is then actuated to take up
a position between two of the studs 4 of a jaw 3, in contact with the
bezel 111, so as to be capable of feeling the corresponding rim 110 of
the eyeglass frame 100.

[0070]Contact between the feeler finger 14 and the bottom of the bezel 111
is maintained by the actuator means exerting a radial return force on the
feeler 10 that is directed towards the bezel 111. This radial return
force thus makes it possible to avoid the feeler finger 14 returning
along one or the other of the flanks of the bezel 111 and escaping
therefrom.

[0071]The electronic and/or computer device 8 then controls the actuator
means of the turntable 6 so that the feeler finger 14 of the feeler 10
moves continuously along the bottom of the bezel 111, remaining in
contact with the bottom of the bezel 111 as a result of said radial
return force.

[0072]During rotation of the turntable, the electronic and/or computer
device 9 reads the three-dimensional coordinates of a plurality of points
along the acquired longitudinal profile P1 of the bezel 111, e.g. 360
points, so as to store an accurate digital image of the profile.

[0073]At the end of this step, the feeler 10 is controlled to return to
its initial position in the center of the turntable 6 and beneath the
eyeglass frame 100.

[0074]This first step of acquiring the three-dimensional shape of the
acquired longitudinal profile P1 could be performed differently in a
variant.

[0075]For example, it could be performed by feeling the bezel 111
optically. Such optical feeling can be performed by acquiring a
three-dimensional digital image of the eyeglass frame and by processing
the digital image electronically so as to identify the position of the
bezel and deduce therefrom the three-dimensional shape of the acquired
longitudinal profile P1.

[0076]This first step of acquisition could also be performed by means of a
database registry accessible to an optician's computer or with the help
of a shared database registry accessible to the computers of a plurality
of opticians working in premises that are remote from one another.

[0077]Under such circumstances, it is then preferable for the database
registry to contain a plurality of records each associated with one
particular type of eyeglass frame reference, i.e. generally an eyeglass
frame model. Each record contains a reference to the type of eyeglass
frame and shape data relating to the shape of a bezel bottom, which shape
is common to all frames of the type. In practice, the reference includes
the name of the eyeglass frame model, while the shape data is made up of
a string of characters providing the three-dimensional coordinates of 360
points along the bottom edge of the above-mentioned bezel.

[0078]In order to acquire the shape of the acquired longitudinal profile
P1, the optician causes the computer to send a request to the database
registry to search for a corresponding record, i.e. to search for a
record having a reference that corresponds to the reference of the
eyeglass frame 100 selected by the wearer. Thereafter, once the record
has been found, the register returns the corresponding stored shape
memory to the optician's computer, which data corresponds in this
instance to the 360 points of the acquired longitudinal profile P1.

[0079]Whatever the method of acquiring the acquired plurality profile P1,
if the eyeglass frame 100 is not already in the reader appliance 1 prior
to the second step, the optician engages it in the holder means 3, 4 of
the appliance in order to acquire the geometrical characteristic H1.

[0080]This geometrical characteristic H1 can then be acquired in various
ways.

[0081]In a first implementation, the geometrical characteristic H1 is
acquired by feeling a cross-section of the bezel 111 and, in said
cross-section, by acquiring the distance between the acquired
longitudinal profile P1 and the front margin 115.

[0082]For this purpose, the electronic and/or computer device 8 initially
controls, in combination, the actuator means for the turntable 6 and for
the support rod 11 so that the feeler finger 14 of the feeler 10 comes
into contact with the bottom of the bezel 111 at some given cross-section
of the rim, i.e. at a predetermined point of the acquired longitudinal
profile P1. By way of example, this point may correspond to the first
acquired point of the acquired longitudinal profile P1.

[0083]Thereafter, the electronic and/or computer device 8 firstly controls
the radial degree of freedom R of the feeler 10 so that it exerts a
constant radial return force enabling its feeler finger 14 to remain in
contact with the rim 110, and secondly controls the axial degree of
freedom Z in such a manner that the feeler finger 14 slides in the given
section of the rim against one of the flanks of the bezel 111 and then
over the front margin 115 of the rim 110. When the feeler escapes from
the rim, i.e. when the feeler finger is no longer in contact with the rim
110, the electronic and/or computer device 8 reads the height difference
between the initial position of the feeler (at the bottom of the bezel
111) and the current position of the feeler (at the height of the rear
margin 115 of the rim). It deduces therefrom the distance H1 between the
bottom of the bezel 111 and the front margin 115 of the rim 110. This
distance H1 then forms the above-mentioned geometrical characteristic.

[0084]In preparation for the third step, this distance H1 is then stored
as the distance between the bottom of the bezel 111 and the front margin
115 at each cross-section of the rim 110.

[0085]In a second implementation, the geometrical characteristic H1 is
acquired by feeling ten distinct cross-sections of the bezel 111 in the
manner described and, at each of the ten cross-sections, by acquiring the
distance between the acquired longitudinal profile P1 and the front
margin 115 of the rim 110.

[0088]It is then preferable for the electronic and/or computer device 8 to
interpolate on the basis of these ten acquired distances H1 to
approximate a distance H1 between the front margin 115 and the bottom of
the bezel 111 at each cross-section of the rim 110. The result of this
interpolation is then stored in preparation for the third step.

[0089]In a third implementation, shown in FIG. 3, the geometrical
characteristic H1 is acquired by sliding the feeler 10 along a generally
longitudinal line P2 of the front margin 115 of the rim 110.

[0090]Advantageously, this generally longitudinal feeling line P2 is
selected to be in register with the first groove or engagement ridge 111,
thus providing the advantage of feeling the front margin 115 close to the
inside face 114 of the rim 110, and thus close to the zone where it is
desired that the front face of the lens should be flush.

[0091]Specifically, the electronic and/or computer device 8 begins by
controlling, in combination, the actuator means for the feeler 10 so that
during a first stage the outside face of the feeler, i.e. specifically
(but not necessarily) the end face of the peg 17, lies under the first
felt or acquired point of the acquired longitudinal profile P1 (e.g. 1
centimeter (cm) below it) and so that, during a second stage, the support
rod 11 of the feeler 10 comes into register with said first point. In
this position "in register" with the first point, the longitudinal axis
A3 of the support rod 11 passes through said first point.

[0092]Thereafter, the electronic and/or computer device 8 controls the
axial degree of freedom Z of the feeler 10 so that it rises to come into
contact with the front margin 115 of the rim 110. This axial freedom of
movement Z is then controlled so that the feeler 10 exerts a constant
axial return force enabling its end face to remain in contact with the
rim 110.

[0093]Finally, the feeler 10 is controlled using its radial and
circumferential degrees of freedom R and THETA and as a function of the
shape of the acquired longitudinal profile P1 so that its end face slides
along the front margin 115 of the rim 100.

[0094]More precisely, the feeler 10 is controlled to move at constant
speed around the axis of rotation A1 in its circumferential freedom of
movement THETA and it is simultaneously controlled in position along its
radial freedom of movement R so that its longitudinal axis A1 remains in
register with the acquired longitudinal profile P1. In this way, the end
face of the feeler 10 slides along a generally longitudinal line P2 of
said front margin 115.

[0095]In a variant, the front margin 115 of the frame could be felt by
means of a different portion of the read head 12 of the feeler 10, e.g.
using the feeler finger 14.

[0096]In another variant, the radial freedom of movement R of the feeler
10 may be controlled so that the support rod 11 of the feeler remains
constantly, not in register with the acquired longitudinal profile P1,
but rather in register with another longitudinal profile of the bezel,
i.e. at a constant distance from the acquired longitudinal profile P1. In
particular, provision can be made for the offset distance between the
longitudinal axis A3 and the acquired longitudinal profile P1 to remain,
throughout the feeling of the front margin 115, constantly equal to the
radius of the end face of the feeler 10 plus 1 mm. Thus, the generally
longitudinal line that is felt on the front margin 115 of the rim extends
close to the inside face 114 of the rim 110. In this way, and as
explained in greater detail below, the ophthalmic lens can be machined so
that once it is engaged in the rim 110, the outline of its front face 121
lies level with the line of the front margin 115 that is beside the
inside face 114 of the rim 110, in a manner that is particularly
attractive.

[0097]When the arrangement of the reader appliance gives the feeler three
degrees of freedom to move in translation, two of these degrees of
freedom to move in translation enable the feeler to move in a plane
substantially parallel to the general plane of the frame, and a third of
these degrees of freedom enables the feeler to move orthogonally to said
plane. With such an arrangement, in order to ensure that the feeler
slides along a generally longitudinal line of the front margin of the
rim, its position is controlled in application of its first two degrees
of freedom as a function of the shape of said acquired longitudinal
profile so that it moves along the front margin 115 of the rim 110, while
remaining in register with the bottom of the bezel 111, and it is
controlled to apply a return force along its third degree of freedom so
as to remain in contact with the rim.

[0098]In any event, when the feeler 10 moves along the front margin 115 of
the bezel, the electronic and/or computer device 8 reads the difference
in height H1 between the bottom of the bezel 111 and the front margin 115
of the rim. More precisely, it reads this difference in level at each of
the 360 felt or acquired points of the longitudinal profile P1. The set
of these differences H1 then forms the above-mentioned geometrical
characteristic.

[0099]In a variant, and as shown in FIG. 4, the feeler 10 may be caused to
slide along a generally longitudinal line P2 of the front margin 115 of
the rim 110, while controlling the position of only one of the three
degrees of freedom of the feeler 10, as explained below.

[0100]In this variant, advantage is taken of the particular shape of the
feeler 10, which by virtue of its bearing shoe 15 is suitable for sliding
along the rim 110.

[0101]More precisely, the step of acquiring the geometrical characteristic
H1 is performed by engaging the bearing shoe 15 against the rim 110 in
such a manner that two bearing zones 112 and 113 of the bearing shoe 15
come into contact respectively with the front margin 115 and the inside
face 114 of the rim 110.

[0102]Thereafter, the electronic and/or computer device 8 controls the
axial and radial degrees of freedom Z and R of the feeler 10
simultaneously to provide a return force so that the feeler exerts a
return force on the rim 110 that extends along the bisector of the
V-shape of the bearing shoe 15, here at 45 degrees relative to the
longitudinal axis A3.

[0103]Finally, the circumferential degree of freedom THETA of the feeler
10 is controlled at constant angular speed so that the bearing shoe 15
slides along the entire rim 110. The electronic and/or computer device 8
then reads simultaneously the axial position of the feeler and deduces
therefrom the difference H1 between the height of the bottom of the bezel
111 and the height of the front margin 115 of the rim.

[0104]More precisely, it determines this difference H1 at each of the 360
felt or acquired points of the longitudinal profile P1. The set of these
differences H1 then forms the above-mentioned geometrical characteristic.

[0105]In a fourth implementation, the geometrical characteristic H1 is
acquired by optical feeling without making contact with the front margin
115 of the rim 110.

[0106]Such optical feeling may be performed by acquiring a
three-dimensional digital image of the eyeglass frame 100 and by
processing said numerical image electronically so as to identify the
position of the front margin 115 of the rim 110 and deduce therefrom the
difference H1 in height between the bottom of the bezel 111 and the rear
margin 115 of the rim at each of the 360 felt or acquired points of the
longitudinal profile P1. The set of these differences H1 then forms the
above-mentioned geometrical characteristic.

[0107]In a fifth implementation, the geometrical characteristic H1 is
acquired by searching for its value in a database registry provided for
this purpose.

[0108]The database registry is preferably of the above-described type. It
contains a plurality of records, each containing a reference to a type of
eyeglass frame together with a geometrical characteristic that relates to
the position of the bezel 111 relative to the front margin 115 of the rim
110 and that is specific to the frames of said type. In practice, the
geometrical characteristic may be formed by a string of characters
providing 360 height differences between the bottom of the bezel 111 and
the rear margin 115 of each of said frames.

[0109]In order to acquire the geometrical characteristic, the optician
then causes the computer to send a request to the database registry to
search for a corresponding record, i.e. to search for a record having its
reference corresponding to the reference of the eyeglass frame 100
selected by the wearer.

[0110]Thereafter, if a corresponding record is found, the registry returns
the corresponding geometrical characteristic to the optician's computer.

[0111]In contrast, if no record is found corresponding to the selected
eyeglass frame 100, then the optician acquires the geometrical
characteristic by means of some other method and then writes a new record
into the database registry associated with said eyeglass frame 100, said
record containing the reference for the frame and the acquired
geometrical characteristic.

[0112]To sum up, whatever the method selected, the electronic and/or
computer device 8 has available at this stage the three-dimensional
coordinates of the 360 points of the acquired longitudinal profile P1 and
of the height difference H1 (as measured or approximated) between the
bottom of the bezel 111 and the rear margin 115 of the rim at each of
said 360 points.

[0113]Then, during the third step, the electronic and/or computer device 8
proceeds to calculate the shape of the deduced longitudinal profile P3 as
a function of said data. The purpose is to ensure that, at the end of the
step of shaping the lens to have this profile, the ophthalmic lens 120
can be engaged in the rim 110 in such a manner that the periphery of its
front face 121 is flush with the front margin 115 of the rim 110.

[0114]The shape of this deduced longitudinal profile is defined herein by
the three-dimensional coordinates of 360 characteristic points.

[0115]The radial and angular coordinates of these 360 points are
calculated herein as a function of the radial and angular coordinates of
the 360 points of the acquired longitudinal profile P1.

[0116]More precisely, they are calculated in such a manner that the
projections of these acquired and deduced longitudinal profiles P1 and P3
onto the general plane of the frame 100 coincide or have the same shape
but at a different scale.

[0117]The scale factor is calculated as a function of the shapes of the
cross-sections of the bezel 111 and of the chamfering groove of the
machining tool 132. This scale factor makes it possible to take account
of the fact that, once said lens is engaged in the rim, the peak of its
engagement ridge 123 (corresponding to the deduced longitudinal profile
P3) is never in contact with the bottom of the bezel (corresponding to
the acquired longitudinal profile P1), but is slightly offset therefrom.

[0118]The axial coordinates along the axis of rotation A1 of the 360
points of the deduced longitudinal profile P3 are calculated as a
function of the axial coordinates of the 360 points of the longitudinal
profile P1 and of the 360 corresponding differences H1.

[0119]Specifically, the axial coordinates of the 360 points of the deduced
longitudinal profile P3 are calculated in such a manner that the front
face 121 of the ophthalmic lens 120 comes flush with the front margin 115
of the rim 110 at a number N of cross-sections of the rim 110. It will be
understood that given the shape differences between the bezel 111 and the
outline of the front face 121 of the ophthalmic lens, it is not possible
for the front face 121 of the lens to be flush with the front margin 115
of the rim over all of its outline.

[0120]This number N can be set by the user. In a variant, provision can be
made for it to be calculated automatically so as to have a maximum value.
In another variant, provision can be made for it to be calculated so that
the mean of the differences between the outline of the front face 121 of
the lens and the front margin 115 of the rim is minimized.

[0121]In the present example, the outline of the front face 121 of the
ophthalmic lens 120 is said to be flush with the front margin 115 of the
rim 110 at a given cross-section of the rim 110 whenever the edge of the
front face 121 of the lens and the front margin 115 of the rim 110 in
this section are situated at the same level along the axis of rotation A1
or are situated so as to extend each other.

[0122]Finally, during a fourth and last step, the shaper appliance 130
proceeds to shape the ophthalmic lens 120.

[0123]The support shafts 131 of the lens and/or the machining tool 132 are
controlled for this purpose as a function of the shape of the deduced
longitudinal profile P3 so as to form, on the edge face of the lens 120,
the engagement ridge 123 with this profile.

[0124]By means of the invention, the crest of the engagement ridge 123 as
obtained in this way extends at a distance from the front face 121 of the
ophthalmic lens 120 that varies in a manner substantially identical to
the manner in which the difference H1 between the front margin 115 and
the bottom of the bezel 111 varies around the rim 110.

[0125]This ensures that once engaged in the rim 110, the front face 121 of
the ophthalmic lens 120 is as flush as possible with the front margin 115
of the rim 110.

[0126]The present invention is not limited in any way to the
implementation described and shown, and the person skilled in the art
knows how to make any variant thereto in accordance with its spirit.

[0127]In particular, the invention finds an advantageous application when
it is implemented by clients (opticians) referred to as "order givers"
who subcontract the fabrication and the shaping of lenses.

[0128]More precisely, consideration is given here firstly to a client
terminal installed beside a client for the purpose of ordering lenses,
and secondly to a manufacturer terminal installed beside a lens
manufacturer for fabricating and shaping lenses.

[0130]The manufacturer terminal has computer means for receiving and
recording the order data transmitted by the client terminal. It also has
a device for fabricating the ophthalmic lens in compliance with the
prescription data, e.g. comprising means for molding the lens and/or for
machining at least one of the optical faces of the lens.

[0131]It also has a shaper appliance for shaping the ophthalmic lens in
compliance with the data relating to the frame. The shaper appliance is
designed in particular to implement the fourth step of the
above-described method.

[0132]In a variant, provision can be made for the manufacturer terminal to
be fitted solely with the shaper appliance and for the means for molding
the lens and/or for machining at least one of the optical faces of the
lens to be located with a manufacturer of unshaped lenses.

[0133]In any event, the lens preparation method is implemented in four
stages.

[0134]During a first stage, the client implements the first two steps of
the above-described method in order to acquire the shape data for the
acquired longitudinal profile P1 together with said geometrical
characteristic H1.

[0135]Then, during a second stage, the order data for a lens is sent via
the client terminal. The order data comprises the optical prescription
for the wearer together with said shape data and said geometrical
characteristic.

[0136]During a third stage, the manufacturer receives the order data. This
data may be received directly from the client terminal, in which case the
manufacturer molds the lens and/or machines at least one of its optical
faces, or else the manufacturer may receive the data from the
manufacturer of unshaped lenses, in which case the order data is
accompanied by an unshaped lens for shaping.

[0137]In any event, in order to calculate the shape of the two optical
faces of the lens, it is preferable to take account not only of the
prescription data for eyesight correction, but also said shape data and
said geometrical characteristic so as to prepare a lens having the
periphery of its front face that is suitable for coming as close as
possible to being flush with the front margin of the frame.

[0138]Finally, during a fourth stage, the manufacturer calculates the
shape of the deduced longitudinal profile P3 as a function of said shape
data and as a function of said geometrical characteristic, implementing a
method analogous to that described above. Finally, the ophthalmic lens
120 is shaped to have the deduced longitudinal profile P3.

[0139]In a variant, this method of preparing lenses could be implemented
differently, using a database registry that is accessible from the client
terminal and from the manufacturer terminal.

[0140]The registry would be analogous to those described above. It would
have a plurality of records each associated with an eyeglass frame type
and each containing a reference and a geometrical characteristic
(relating to the position of the bezel relative to the front margin of
the rim) that are specific to frames of the corresponding type. In
practice, the geometrical characteristic is constituted by a string of
characters comprising 360 height differences between the bottom of the
bezel and the front margin of the frame. Preferably, each record also
includes the three-dimensional coordinates of the 360 points of an
acquired longitudinal profile.

[0141]In any event, during a first step, the client determines an eyeglass
frame reference, e.g. corresponding to the name of the frame model, and
then sends the reference to the manufacturer terminal, via the client
terminal.

[0142]During a second step, the manufacturer searches the database
registry for a record including said reference. The corresponding
geometrical characteristic can then be read from the record. The
three-dimensional coordinates of the 360 points of the corresponding
acquired longitudinal profile can also be read, unless the client has
already delivered the coordinates.

[0143]Thereafter, from these coordinates and from said geometrical
characteristic, the manufacturer deduces the shape of the deduced
longitudinal profile using a method of the type described above.

[0144]Finally, during a third step, the manufacturer shapes the ophthalmic
lens to match the deduced longitudinal profile.

[0145]The description above relates to rimmed eyeglass frames. However the
method as described is equally applicable to half-rimmed eyeglass frames.

[0146]It is recalled that such eyeglass frames have half-rims
interconnected by a bridge and each provided with a temple. Each half-rim
presents an inside face along which there runs an engagement ridge, lying
between a rear margin that is to face towards the face of the wearer of
the eyeglass frame, and an opposite, front margin.

[0147]The geometrical characteristic corresponding to the distance between
the peak of the engagement ridge and the front margin of the half-rim may
be acquired in particular using any of the implementations explained
above.

[0148]The lens is then shaped with the help of a shaper appliance having a
grooving grindstone, i.e. a grindstone presenting a projection, like a
negative, with a machining profile that is complementary to the section
of the engagement groove that is to be obtained in relief in the edge
face of the lens to be machined.

[0149]Such a shaper appliance, well known to the person skilled in the
art, is described for example in document FR 2 874 526 or in document EP
0 176 401, or its equivalent U.S. Pat. No. 4,640,055.